Equilibrium analysis for heavy metal cation removal using cement kiln dust

2014 ◽  
Vol 70 (6) ◽  
pp. 1011-1018 ◽  
Author(s):  
Mohamed El Zayat ◽  
Sherien Elagroudy ◽  
Salah El Haggar
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Removal ◽  
Equilibrium Constants ◽  
Surface Complexation ◽  
Chemical Precipitation ◽  
Equilibrium Analysis ◽  
Cement Kiln Dust ◽  
Cement Kiln ◽  
Kiln Dust

Ion exchange, reverse osmosis, and chemical precipitation have been investigated extensively for heavy metal uptake. However, they are deemed too expensive to meet stringent effluent characteristics. In this study, cement kiln dust (CKD) was examined for the removal of target heavy metals. Adsorption studies in completely mixed batch reactors were used to generate equilibrium pH adsorption edges. Studies showed the ability of CKD to remove the target heavy metals in a pH range below that of precipitation after an equilibrium reaction time of 24 h. A surface titration experiment indicated negative surface charge of the CKD at pH below 10, meaning that electrostatic attraction of the divalent metals can occur below the pH required for precipitation. However, surface complexation was also important due to the substantive metal removal. Accordingly, a surface complexation model approach that utilizes an electrostatic term in the double-layer description was used to estimate equilibrium constants for the protolysis interactions of the CKD surface as well as equilibria between background ions and the sorbent surface. It was concluded that the removal strength of adsorption is in the order: Pb > Cu > Cd. The experiments were also supported by Fourier transform infrared spectroscopy (FTIR).

Modeling of heavy metals removal from aqueous solution using activated carbon produced from cotton stalk

2013 ◽  
Vol 67 (7) ◽  
pp. 1612-1619 ◽  
Author(s):  
Mohamed El Zayat ◽  
Edward Smith
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Activated Carbon ◽  
Metal Removal ◽  
Ph Value ◽  
Equilibrium Constants ◽  
Surface Complexation ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Carbon Surface

Activated carbon produced from cotton stalks was examined for the removal of heavy metal contaminants. Adsorption studies in completely mixed batch reactors were used to generate equilibrium pH adsorption edges. Continuous flow experiments using the activated carbon in fixed beds were conducted to determine heavy metal breakthrough versus bed volumes treated. At given pH value in the range 5–7, the adsorption capacity was similar for copper and lead and clearly greater than for cadmium. A surface titration experiment indicated negative surface charge of the activated carbon at pH > 6, meaning that electrostatic attraction of the divalent heavy metals can occur below the pH required for precipitation. Substantive metal removal below the pH of zero charge might be due to surface complexation. Accordingly, a surface complexation model approach that utilizes an electrostatic term in the double-layer description was used to estimate equilibrium constants for the protolysis interactions of the activated carbon surface as well as equilibria between background ions used to establish ionic strength and the sorbent surface. Pb(II) adsorption edges were best modeled using inner-layer surface complexation of Pb2+, while Cd(II) and Cu(II) data were best fit by outer-layer complexes with Me2+. The full set of equilibrium constants were used as input in a dual-rate dynamic model to simulate the breakthrough curves of the target metals (Pb, Cu and Cd) from fixed bed experiments and to estimate external (or film) diffusion and internal (surface) diffusion coefficients.

Limed sewage sludge effects on nutrient status and metal fractions in acidic soils

1999 ◽  
Vol 79 (1) ◽  
pp. 173-182 ◽  
Author(s):  
R. R. Simard ◽  
S. Beauchemin ◽  
M. R. Laverdière
Keyword(s):  
Heavy Metal ◽  
Sewage Sludge ◽  
Water Soluble ◽  
Cement Kiln Dust ◽  
Cement Kiln ◽  
Acidic Soils ◽  
Mn Toxicity ◽  
Extractable P ◽  
The Impact ◽  
Kiln Dust

The potential impacts of limed sludge on nutrient and heavy metal bioavailability must be studied for their safe use on acidic soils. The objective of this study was to assess the impact of limed sludges on six acidic soils from eastern Canada. CaCO3 and raw sewage sludges (RSS) stabilized with either CaO (CaO + S) or cement kiln dust (CKD + S) were added to soils in amount necessary to reach pH 6.5 and the mixtures were then incubated for 64 d. CaO + S treatments were the most efficient to neutralize soil acidity. After 10 d of incubation, the Sr-citrate extractable P was significantly increased by the CaO + S treatment in low P sorption soils. The extractable K, Zn and Cu contents were also slightly increased by CaO + S compared to CaCO3 whereas CKD + S resulted in an excessive soil exchangeable K content. After 64 d, labile Al content was decreased by all liming amendments. RSS and CaO + S tended to increase labile Cu and Mn contents. The RSS increased NaOH-extractable Cu but the treatments had no significant effects on the labile and stable forms of heavy metals. A combination of CaO + CKD to stabilize sewage sludge would be more suitable to provide appropriate levels of P and K without resulting in large increases in extractable heavy metal contents. Key words: pH, extractable P and K, cement kiln dust, Al and Mn toxicity, Cu fractions, water-soluble metals

Dominant Mechanisms for Metal Removal from Acidic Aqueous Solutions by Cement Kiln Dust

2016 ◽  
Vol 36 (2) ◽  
pp. 209-216 ◽  
Author(s):  
Abbas H. Sulaymon ◽  
Ayad A. H. Faisal ◽  
Qusey M. Khaliefa
Keyword(s):  
Aqueous Solutions ◽  
Metal Removal ◽  
Cement Kiln Dust ◽  
Cement Kiln ◽  
Kiln Dust

The use of cement kiln dust for the removal of heavy metal ions from aqueous solutions

2005 ◽  
Vol 83 (4) ◽  
pp. 210-214 ◽  
Author(s):  
A. Pigaga ◽  
R. Juškenas ◽  
D. Virbalytė ◽  
M. G. Klimantavičiūtė ◽  
V. Pakštas
Keyword(s):  
Heavy Metal ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Cement Kiln Dust ◽  
Cement Kiln ◽  
Kiln Dust

scholarly journals Magnetic Hydroxyapatite for Batch Adsorption of Heavy Metals

2021 ◽  
Vol 287 ◽  
pp. 04005
Author(s):  
Khee Chung Hui ◽  
Norashikin Ahmad Kamal ◽  
Nonni Soraya Sambudi ◽  
Muhammad Roil Bilad
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Removal ◽  
Aqueous Media ◽  
Heavy Metal Removal ◽  
Calcium Nitrate ◽  
Chemical Precipitation ◽  
Batch Adsorption ◽  
Calcium Nitrate Tetrahydrate ◽  
Removal Of Heavy Metals

In this work, magnetic hydroxyapatite or hydroxyapatite-iron (III) oxide (HAp-Fe3O4) composite was used as the adsorbent of heavy metals and the performance was evaluated using the batch test. The presence of heavy metals in the effluent from wastewater discharge can be toxic to many organisms and can even lead to eye burns. Therefore, hydroxyapatite synthesized from the chemical precipitation of calcium nitrate tetrahydrate and diammonium hydrogen phosphate solutions is used to remove heavy metal in aqueous media. Magnetic properties of Fe3O4 can help prevent formation of secondary pollutants caused by the loss of adsorbent. The synthesized HAp-Fe3O4 can remove cadmium, zinc and lead effectively, which is up to 90% removal. Reusability study shows that the adsorbent could retain heavy metal ions even after four cycles. The percentage removal of heavy metals maintains at around 80% after four times of usage. The composite of HAp-Fe3O4 demonstrates good performance and stability which is beneficial for heavy metal removal in the future.

Heavy Metal Removal Using Bound Macrocycles

1991 ◽  
Vol 23 (1-3) ◽  
pp. 301-308 ◽  
Author(s):  
R. M. Izatt ◽  
R. L. Bruening ◽  
M. B. Borup
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Metal Removal ◽  
Equilibrium Constants ◽  
Heavy Metal Removal ◽  
Pilot Scale ◽  
Heavy Metal Cations ◽  
Gel Beads ◽  
Removal Of Heavy Metals ◽  
Alkaline Earth Cations

Aza macrocycles bound to silica gel beads were found to selectively remove heavy metal cations such as Pb2+, Cd2+, Ag+, and Hg2+ from aqueous solutions. These bound macrocycles have a virtually infinite selectivity of binding with heavy metals over alkali and alkaline earth cations. The material is very stable and can be reused hundreds of times. Columns may be regenerated using an acidic eluent solution. Equilibrium constants were determined by column tests. Removal of heavy metals was demonstrated in bench scale tests using a synthetic contaminated water and in pilot scale tests using a naturally contaminated river water. Heavy metal concentrations could be effectively reduced to the µg/L level using the process.

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